#define _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>
#define NAME_LEN 100
#define STUDENT_LEN 100
struct score {
    char name[NAME_LEN];
    int sn;
    float score;
}student[STUDENT_LEN];
int main(void)
{
    float avg, sum;
    int n, i;

    scanf("%d", &n);

    for (i = 0; i < n; i++) {
        scanf("%d", &student[i].sn);
        scanf("%s", student[i].name);
        scanf("%f", &student[i].score);
    }

    sum = 0;
    for (i = 0; i < n; i++) {
        sum += student[i].score;
    }

    avg = sum / n;
    printf("%.2f", avg);

    return 0;
}
